The Hyper-V VM 'vmname' is in a "branch" state
compared to the last backup. Incremental Forever - Incremental backup
cannot be performed. An Incremental Forever - Full backup will be
performed instead.
Explanation
The VM state is in a "branch" compared to the last backup. This
causes a fallback to Incremental Forever - Full as backup consistency
in this state is not guaranteed.
System action
An Incremental Forever - Full backup will be performed.